Development of Marble Dust Based Sustainable Cementitious Grout for Semi Flexible Pavement Application

Abstract

The topmost layer of grouted macadam comprised of a semi flexible material that has numerous advantages over concrete and conventional bitumen. It is resistant to rutting and has a certain amount of flexibility. It is made up of a cementitious slurry that is grouted into a framework of open-graded asphalt that has voids between 25% and 35% in volume. Because of its impermeable covering, it also prevents water from seeping into the base of the structure. This investigation focuses on Marble Dust (MD)-based cementitious grouting for semi flexible pavement applications. The experimental design includes preparation of Marble Dust (MD) based sustainable cementitious grout with 6 different percentages of marble dust ranging from 0% to 25% substitution in cement. Water to cement ratio (w/c) for preparation of grout ranges from 0.35 to 0.5 at an increment of 0.5 based on previous research studies and a constant superplasticizer of 0.5% to achieve the flowability. Mortar was prepared using Hobart Mortar mixer and flowability at each replacement level were recorded. Compressive strength tests of grouts (7-days & 28-days) were performed at each replacement level in triplicate. Response Surface Methodology (RSM) was also used to optimize the independent variable known as factor (MD, w/c) and to achieve desired outcome that is response (Flow, Compressive strength) Based on experiment results and RSM optimization with predicted model R² of greater than 0.9 it was concluded that up to 15% of cement replacement by MD with w/c of 0.4 reveals identical results to the control mix and within specification limits of grout for semi-flexible pavement application. Microstructure analysis SEM and EDS were performed on optimum and control grouts to analyze the behavior of marble dust in grout. From analysis it was confirmed that MD being inert filler improved density by reducing pores, cracks, and lower Ca/Si ratio. Open graded specimens were prepared at OBC of 3.0% and cement grout (with optimum combination) was poured on surface with infiltration ranged from 94% to 97%. The final composite that is Semi-flexible pavement prepared with MD based sustainable cementitious grout were subjected to different physical and performance tests as per standards. Marshall stability increased up to 70%, Tensile strength ratio of SFM-MD is 30% enhanced as compared to HMA, stiffness modulus enhanced at high and low temperature, dynamic modulus performed double the HMA at high temperature and low frequency and fuel resistance of semi-flexible mix increased more the 600% as compared to conventional HMA. The new hybrid semi-flexible and joint-free topping is superior for durability and wear resistance, according to findings.